This invention relates generally to a humidifier device, and more particularly, to an electrical humidifier device in which energization is delayed to ensure that a liquid reservoir cavity is fully filled.
Humidifier devices typically include a reservoir cavity and a humidification unit such as a heater coil, an ultrasonic transducer or an impeller that can be energized to induce dispersion of liquid retained by a reservoir cavity. Most humidification units can be damaged if energized without a sufficient level of water in the reservoir cavity. For example, a heating element can burn out if heated while dry and then quenched in water, an ultrasonic transducer can be burned out if it oscillates without being covered by a sufficient height of liquid or an impeller modem can undesirably rotate at a potentially harmful excessive rpm with operating without a sufficient water load. Consequently, most humidifier devices employ a liquid level sensor that will deenergize the humidification unit when the level of liquid in the reservoir cavity falls below a given minimum level.
However, typical liquid level sensing devices such as float operated switches exhibit a form of backlash that inherently responds to a slightly lower liquid level during reservoir cavity filling than to a falling level of reservoir cavity liquid level. That is, a typical sensing switch will be closed during reservoir filling operations at a level slightly lower than the reducing liquid level required to induce switch deactivation. Since typical sensing devices exhibit some level of operating tolerance, they are generally designed, therefore, to produce switch activation at a liquid level somewhat below the desired reservoir liquid operating level. Consequently, the switches in conventional devices can be activated to energize and thereby possibly damage the humidification unit before the reservoir cavity has been adequately filled, and possibly damaged. This problem is exacerbated in those devices employing a liquid supply tank that feeds water to the liquid cavity at a relatively slow rate.
The object of this invention, therefore, is to provide an improved humidifier device that ensures adequate filling of a reservoir cavity before energization of a humidification unit.